The present invention relates generally to electronic appliance controllers and, more particularly, to an appliance electronic control system which tends to maintain a constant total cycle time, and thus an accurate "Time Remaining" display, notwithstanding variations in the actual time required for a water fill operation.
The subject invention may be implemented as a part of an appliance electronic control system which is disclosed in concurrently-filed application Ser. No. 07/968,991, filed Oct. 30, 1992, by Thomas R. Payne and Steven A. Rice, entitled "Reconfigurable Appliance Electronic Control System with Automatic Model Determination, Internally Restructurable Control and Flexible Programmable Test Modes", and concurrently-filed application Ser. No. 07/969,139, filed Oct. 30, 1992, by Thomas R. Payne, William W. Wead and Steven A. Rice, entitled "Appliance Electronic Control System with Programmable Parameters Including Programmable and Reconfigurable Fuzzy Logic Controller", the entire disclosures of which are hereby expressly incorporated by reference.
Application Ser. No. 07/968,991 discloses a microcontroller-based electronic control system which is able to handle a variety of different appliances which are members of a family of commercial laundry products In a particular embodiment disclosed, the appliance electronic control system is applicable to each of a two-speed clothes washer, a one-speed clothes washer, an electronic dryer and a gas dryer.
A desirable feature in such appliances is a "Time Remaining" display which indicates cycle time remaining based on the state of a count down timer maintained by the controller. In a commercial, coin-operated laundry environment, a dryer cycle is entirely time driven, so little difficulty is involved in maintaining an accurate "Time Remaining" display The controller simply initializes the count down timer with the total cycle time, and then decrements the count down timer at regular predetermined intervals.
However, a clothes washer is both time and event driven, such that an accurate measure of cycle time remaining is more difficult to achieve. Thus, in the case of a washing machine, in order to initialize the count down timer, the control system must sum the time requirements of the various portions of the cycle, referred to herein as operational modes. These operational modes include wash water fill time, soak time, wash agitate time, spin time, rinse fill time, rinse agitate time, final spin time, and several pauses that occur between these operational modes. The pauses are required in order to allow the machine to come to a complete stop upon completion of one operational mode and the commencement of another operational mode in certain situations. In particular, a washing machine would likely be damaged if an attempt were made to switch instantaneously from an agitate mode to a spin mode, since a change in motor direction is involved.
The operational mode times just mentioned are under the direct control of the controller, with the exception of wash water fill and rinse water fill. Since the cessation of water fill is event driven, based on closing of a water level sensor switch or equivalent, rather than time driven, the actual time required to fill is known only after the water fill has occurred. This prevents an accurate initializing of the count down timer and thus prevents an accurate display of time remaining in the wash cycle.
In the past, this problem has been addressed by simply stopping the timer during water filling operations. However, when such an approach is employed, the displayed "Time Remaining" has little actual meaning since the operational cycle is not complete after the number of displayed minutes.
Another approach in the context of an electronically-controlled washing machine is to maintain a history of each particular machine to learn the actual fill times for that particular machine. This may be accomplished using a data filtering technique whereby a running average is kept for the fill time, and running average data is used in a time calculation for determining nominal fill time. This approach would offer a great deal of accuracy in estimating cycle time and thus in displaying "Time Remaining", but the displayed time may be different for different machines. It is considered less desirable by many users, especially in commercial laundry applications, to have a number of machines sitting side by side with different displayed cycle times.